Better font anti-aliasing on 1080p or low resolution monitors on recent macOS versions

Problem: after macOS Mojave apparently Apple removed sub-pixel anti-aliasing - an effect that makes fonts smoother and less pixelated/jaggy.

My workaround: use a VGA connection - and maybe a DisplayPort connection.

The story:

If the edges of your fonts looked jagged or pixelated then one will end up finding that anti-aliasing as part of font rasterization is part of what needs to happen for smooth fonts. If using Microsoft Windows then the ClearType settings in Windows are something to investigate.

But in recent macOS versions Apple seems to base the system behaviour on folks using HiDPI monitors and so one can see jagged fonts on a full HD monitor. I discovered this connected to a 1080p Full HD monitor using a Mini DisplayPort to DVI adapter.

Mitigation: try a VGA connection (and maybe a DisplayPort connection)

However I usually used a Mini DisplayPort to VGA adapter to connect to that monitor - and switching back from Mini DisplayPort to DVI to Mini DisplayPort to VGA confirmed that the VGA connection saw better font rendering (Mini DisplayPort adaptors were connecting to Thunderbolt 2 port on the Mac).

This was on macOS Monterey - so cannot confirm for all newer versions of macOS. But if you use a 1920 x 1080 (1080p) monitor or a lower resolution one then I suggest trying a VGA adapter and seeing if the VGA output has better anti-aliasing and font display than a digital input to the monitor such as HDMI or DVI.

A Mini DisplayPort to DisplayPort connection on a 1920 by 1200 pixel monitor also looked comparatively good - suggesting trying a DisplayPort connection if you have a monitor with a DisplayPort input.

What definitely looked bad for font rendering was Mini DisplayPort to DVI.

Software mitigation for 4K monitors:

Apparently this issue may crop up even on 4K Monitors - e.g. this Reddit comment - in which case programs like BetterDisplay may be able to help. In the case of BetterDisplay this involves adding a resolution variant that is flagged as HiDPI - even if the screen is not natively recognised as HiDPI (though one has to sacrifice one pixel of the width as the OS does not allow two variants of the exact same resolution).

Comment: why does VGA work better?

In terms of a logic to why things might be better on VGA at this resolution:- I have seen rendering speed being mentioned as a reason to turn off sub-pixel antialiasing in a context in which monitors can have much higher refresh rates as well as higher pixel counts. This Apple Developer talk covers ways in which displays might handle higher refresh rates. So while I cannot draw confident links between what I have observed and Apple changes it does seem to fit issues discussed in more than the Apple forums post and digital monitor connections having to handle HiDPI monitors (that do not need subpixel rendering) and faster refresh rates (that put a premium on faster graphics rendering especially in context of HiDPI displays) it does make speed seem plausible cause for a change in font treatment.

So it does make a little more sense that VGA output might get a font treatment that takes more time but looks better at lower resolutions. Because in this situation - due to the age of VGA - the developers can be confident:-